The Surge - Boss Weapons V2.0

P.A.X.

Do not let him damage himself with his rockets, instead you need to break the covers on the front of the legs and then hit the leg that's still on the ground during his stomp.

LU-74 Firebug

Firebug Throttle v2.0 - Twin rigged

You need to destroy all the legs before killing the boss.

Big Sister

Spitfire Rod v2.0 - Staff

You need to kill Big Sister with at least 2 or more wielding torch still intact.

R&D's Bloodied Proteus Mini-Boss

Parsifal v2.0 - 1 handed - confirmed

Rip off his Right Arm.

Bonus: The Mini-Boss will respawn so you can farm all the Bloodied Proteus set off of him.

The Black Cerberus

MG Judge v2.0 - Heavy Duty

You need to rip off his Right Arm.

Bonus: Full Black Cerberus set in 1 fight.

To receive the full Black Cerberus Armor in one go, make sure the two giant white canisters (no confirmation that just destroying 1 canister works, I'd destroy both to be sure) with Online have been destroyed by the summoned PAX ( instead of shooting a salve of missiles like the first encounter, this PAX will shoot 3 single missiles, stand in front of the cannisters and dodge before impact). This will also stop BC from spawning more PAXes during the fight. You are able to destroy both canisters with a single PAX. When you rip off the Right Arm at the end of the fight, all the pieces will unlock.